Electrolytic cell having an intermediate sub-component connecting layer and process for fabricating the same

ABSTRACT

The present invention is directed to an electrolytic cell and associated process for fabrication, wherein the cell utilizes an intermediate sub-component connecting layer. This layer comprises an electrolyte which, in an at least partially cured state, is at least partially sandwiched between an electrolyte on a first sub-component and an electrolyte on a second sub-component. Prior to full curing of the intermediate sub-component connecting layer, the cell is oriented into a desired product configuration. Once such a configuration is obtained, the intermediate sub-component connecting layer is fully cured to, in turn, maintain the cell in the desired product configuration without concern of misalignment or mechanical degradation between the various sub-components and/or the cell.

[0001] This application depends from Provisional Patent ApplicationSerial No. 60/008,434 entitled USE OF AN INTERMEDIATE LAYER (TIE-COAT)TO IMPROVE SUB-COMPONENT ADHESION, filed Dec. 11, 1996.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is directed to electrolytic cells and theirfabrication, and, more particularly, to an electrolytic cell with anintermediate sub-component connecting layer which ties together othersub-components, such as an anode and cathode, and which facilitatesoperative alignment and securement of the sub-components duringformation of a desired product configuration, without jeopardizingmechanical integrity of the fully fabricated cell.

[0004] 2. Background Art

[0005] Electrolytic cells fabricated from various sub-components,wherein one of the sub-components is an electrode, are well known in theart. Indeed, in such prior art devices and processes, adhesion betweenthe electrodes and electrolyte is typically accomplished by one of threeways. First, when a liquid electrolyte is utilized in a cell, the cellis maintained under pressure so as to avoid the loss of contact betweenthe sub-components. To maintain such pressure for a round cell, the cellis wound so as to create an inner tension. When a prismatic cell isfabricated, spring loading is utilized to maintain the necessarypressure. Second, when a high temperature polymer electrolyte is used(such as PEO or PVdf), the sub-components are fused together by pressureand heat. Third, when a gel electrolyte is used, the sub-components areplaced in contact with each other, and then the electrolyte precursor ispolymerized to a monolithic gel electrolyte by for example, UV, EB orheat curing.

[0006] Although such prior art does enable attachment of the varioussub-components together, several problems nevertheless exist.Specifically, in many cases, the sub-components do not uniformly adhereto each other, thereby resulting in a cell with poor performancecapabilities. Furthermore, in such prior art cells, mechanicaldegradation often occurs when, for example, the cell is bent or rolledinto a desired product configuration. Additionally, such bending orrolling also may result in an electrolytic cell having the edges of theelectrode misaligned with each other—thereby resulting in poor cellperformance and short circuiting.

SUMMARY OF INVENTION

[0007] The present invention is directed to an electrolytic cell havingan intermediate sub-component connecting layer for facilitating securedoperative alignment between the electrodes of the cell. The electrolyticcell includes a first electrolytic sub-component having a firstelectrolyte applied therewith, and a second electrolytic sub-componenthaving a second electrolyte applied therewith. The intermediatesub-component connecting layer is secured to the first and secondelectrolytes and may comprise an electrolyte of the same or differentcomposition as that of the first and/or second electrolytes.

[0008] In a preferred embodiment of the invention, the intermediatesub-component connecting layer comprises means for enablingrolling/winding and bending of the electrolytic cell without causingmechanical degradation to the electrolytic cell or any of the associatedsub-components. As will be explained, after rolling and bending hasoccurred, the intermediate sub-component connecting layer will be curedso as to maintain the electrolytic cell in the desired productconfiguration; without the need of additional mechanical aids such assprings or casings. As will be understood, the first and secondelectrolytic sub-components may comprise an anode and cathode. The useof the term sub-component is due to the fact that such anodes andcathodes may be pre-fabricated to include the current collector, primer,active material and an associated electrolyte.

[0009] In another preferred embodiment of the invention, theintermediate sub-component connecting layer comprises a polymerizablegel electrolyte or a high temperature polymer. Such an electrolytefurther includes means for penetrating into the first and secondelectrolytes to, in turn, promote securement therebetween.

[0010] The present invention also contemplates a process for fabricatingan electrolytic cell comprising the steps of 1) fabricating the firstelectrolytic sub-component with a first electrolyte; 2) fabricating asecond electrolytic sub-component with a second electrolyte; 3) applyingan intermediate sub-component connecting layer, comprising an at mostpartially cured/polymerized electrolyte (the term cured will beunderstood to include polymerization), onto one of the first and secondelectrolytes of the first and second electrolytic sub-components,respectively; 4) attaching the other one of the electrolyticsub-component to the intermediate sub-component connecting layer so thatat least a portion of the intermediate sub-component connecting layer issandwiched between the first and second electrolytes; 5) orientating theelectrolytic cell into a desired configuration while enabling relativesliding between the first and second electrolytic sub-components so asto facilitate operative alignment therebetween; and 6) fully curing theintermediate sub-component connecting layer after the desiredconfiguration and alignment have been obtained to, in turn, maintain theelectrolytic cell in the desired configuration after such full curing.

[0011] In the present process, the step of fabricating the first andsecond electrolytic sub-components further comprises the step offabricating at least one of the first and second electrolyticsub-components with an electrolyte which is at most partially cured.

[0012] In addition, the process also contemplates the steps of allowingat least a portion of the intermediate sub-component connecting layer topenetrate into at least a portion of the first and second electrolytesprior to the step of fully curing the intermediate sub-componentconnecting layer; and, curing the at least one of the first and secondelectrolytes. It is important to note here that the curing of the firstand second electrolytes does not need to be accomplished prior to thestep of fully curing the intermediate sub-component connecting layer.

[0013] The intermediate sub-component connecting layer may include aliquid with polymerizable monomers. Inasmuch as the intermediatesub-component connecting layer is not in a fully cured state, the liquidstate will facilitate the desired slidability between the sub-componentswhen trying to achieve a desired product configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 of the drawings is a schematic diagram of the presentelectrolytic cell having an intermediate sub-component connecting layer;and

[0015]FIG. 2 of the drawings is a schematic diagram of the presentelectrolytic cell having an intermediate sub-component connecting layer.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] While this invention is susceptible of embodiment in manydifferent forms, there is shown in the drawings and will be described indetail, one specific embodiment with the understanding that the presentdisclosure is to be considered as an exemplification of the principlesof the invention and is not intended to limit the invention to theembodiment illustrated.

[0017] Electrolytic cell 10 is shown in FIG. 1 as comprising firstelectrolytic sub-component 12, second electrolytic sub-component 14 andintermediate sub-component connecting layer 16. First electrolyticsub-component 12 includes current collector 18, primer material 19,active material 20 and first electrolyte 21. Although several materialscan be used, current collector 18 will be described, for illustrationpurposes only, as comprising copper, although many other conventionalmaterials, as would be easily understood to those with ordinary skill inthe art, are likewise contemplated for use. The same holds true for theparticular primer 19 and the active electrode material 20. As will bemore fully explained, first electrolyte 21 preferably comprises a gel orhigh temperature polymer electrolyte.

[0018] Second electrolytic sub-component 14 also comprises a currentcollector 22, primer 23, active material 24 and second electrolyte 25.Again, each of the materials associated with the second electrolyticsub-component are conventionally available and the particular types ofmaterials to be used would be readily understood to those with ordinaryskill in the art. However, for the purposes of the present explanation,current collector 22 may comprise aluminum.

[0019] Although the term “sub-component” has, and will continue to beused throughout the present Specification, it should be understood thatsuch a term (with respect to sub-components 12 and 14) arerepresentative of a fully fabricated anode (12) and cathode (14); eachof which include the previously identified associated primer, activematerial and electrolyte. Intermediate sub-component connecting layer 16comprises an electrolyte which can be of the same composition as eitherfirst and/or second electrolytes 21, 25, respectively, so long as all ofthe electrolytes, when associated with each other, exhibit the necessaryionic conductivity required to enable operable performance of cell 10.

[0020] Intermediate sub-component connecting layer 16 is shown in FIG. 1and FIG. 2 as having at least a portion sandwiched between first andsecond electrolytes 21 and 25, respectively. As will be explained morefully with respect to the process for fabricating electrolytic cell 10,intermediate sub-component connecting layer 16 will be applied to firstand second electrolytes 21 and 25, respectively, which are, at most, ina partially cured state. However, even if partially cured, intermediatesub-component connecting layer 16 will remain in a substantially liquidphase after application on to, and sandwiching between first and secondelectrolytes 21 and 25, respectively. Indeed, the liquid phase ofintermediate sub-component connecting layer serves two purposes: 1) itfacilitates penetration (See FIG. 2) and, in turn, excellent securementwith the first and second electrolytes; and 2) it enables operativeslidability to occur relative to the first and second electrolyticsub-components. As will be more fully explained, such slidabilityenables proper alignment of the edges of the electrolyticsub-components, relative to each other, during (and after) bending orfolding of electrolytic cell 10 into a desired configuration. Once thedesired configuration is made, intermediate sub-component connectinglayer 16, and, if necessary, first and second electrolytes 21 and 25,respectively, will be exposed to final curing which will maintainelectrolytic cell 10 in the desired configuration while also maintainingexcellent adhesion between the various sub-components.

[0021] With respect to the fabrication of electrolytic cell 10, and aspreviously explained, it will be assumed that first and secondelectrolytic sub-components 12, 14, respectively, comprisepre-fabricated electrodes (anode and cathode) with desired currentcollectors, primers, active materials and electrolytes associatedtherewith. Again, the particular materials used, and the associatedapplication processes for the elements of the first and secondelectrodes/electrolytic sub-components, onto the respective currentcollectors, are conventionally known and understood by those withordinary skill in the art. However, it is also contemplated thatalthough pre-fabricated sub-components have been identified for use inthe present disclosure, that non-pre-fabricated sub-components can alsobe used and conventionally assembled in accordance with the teachings ofthe present disclosure.

[0022] After the desired sub-components have been selected, intermediatesub-component connecting layer 16, which may comprise a liquid withpolymerizable monomers in an at most partially cured state, is thenapplied onto either first electrolyte 21 or second electrolyte 25. Theelectrolyte composition of the connecting layer may be the same as thatof the first or second electrolyte 21, 25, respectively.

[0023] Although the particular composition of the various electrolytesand, more particularly, intermediate sub-component connecting layer 16,are not of great significance to the teaching and understanding of thepresent invention, it is nevertheless contemplated that a gel or hightemperature polymer electrolyte be used. For example, a PC gelelectrolyte 16 having the following formulation was used (although, asunderstood to those with ordinary skill in the art, the presentinvention is in no way limited to this particular formulation or type ofelectrolyte): PC GEL FORMULATION g % PC 117.75 78.5 LiAsF₆ 18 12.0 PEO0.75 0.5 PHOTOMER 4050 9 6.0 PHOTOMER 4158 4.5 3.0 TOTAL 150 g 100.00

[0024] After using conventional mixing and fabrication techniques, thetotal viscosity of the PC gel electrolyte was measured at approximately500 cps. The prepared PC gel was then coated onto first electrolyte 21(which may, for example, comprise a SPE), and allowed to at leastpartially penetrate into the first electrolyte (See FIG. 2). After suchhas occurred, second electrolyte sub-component 14, and in turn secondelectrolyte 25, was placed over intermediate sub-component connectinglayer 16, to, in turn, sandwich at least a portion of it between thefirst and second electrolytes. As previously stated, although the firstand second electrolytes and the intermediate sub-component connectinglayer may be in an at most partially cured state, the intermediatesub-component connecting layer will remain in a substantially liquidstate relative to the first and second electrolytes to, in turn,facilitate desired slidability of the first and second electrolyticsub-components relative to each other.

[0025] After all of the sub-components have been applied to each other(FIG. 2), electrolytic cell 10 can be manipulated into a desired productconfiguration. Inasmuch as the first and second electrolyticsub-components will slide relative to each other, misalignment (such asedges inadvertently overlapping, or hanging over one another) andmechanical degradation between the various sub-components which wouldotherwise occur during, for example, folding, bending, rolling and/orwinding of the cell, will be avoided. Accordingly, once the desiredproduct configuration has been obtained, intermediate sub-componentconnecting layer 16, and, if necessary, first and second electrolytes21, 25, respectively, will be exposed to a “full” curing/polymerizationprocess (as those terms are understood in the art). Once such fullcuring has occurred, electrolytic cell 10 will be maintained in thedesired product configuration, without the need for additionalmechanical devices, such as casings or springs. In addition, since theproduct configuration has occurred before curing of the electrolyte(s),mechanical degradation and loss of adhesion between the varioussub-components (which may otherwise occur during folding, bending and/orrolling of an electrolytic cell) is substantially precluded.

[0026] As an additional benefit of the present invention, it is furthercontemplated that when, for example, a stack of electrolytic cells areto be associated with each other (such as in a battery pack), theindividual cells can be placed into a box or package prior tocuring/polymerization of the electrolyte(s), such as the intermediatesub-component connecting layer. Accordingly, inasmuch as the box orpackage will have a specific internal geometry, the stacked cells may beconfigured into a conforming relationship with the internal geometry.After the stacked cells have been placed and properly configured/formedwithin the box or package, the electrolyte(s) of the stacked cells willthen be allowed to cure/polymerize, to, in turn, maintain theconfiguration of the stacked cells in conformance with the internalgeometry of the box or package.

[0027] The foregoing description merely explains and illustrates theinvention and the invention is not so limited except insofar as theappended claims are so limited, as those having skill in the art whohave the present disclosure before them will be able to makemodifications and variations therein without departing from the scope ofthe invention.

What is claimed is:
 1. An electrolytic cell having an intermediatesub-component connecting layer comprising: a first electrolyticsub-component having a first electrolyte associated therewith; a secondelectrolytic sub-component having a second electrolyte associatedtherewith; and an intermediate sub-component connecting layer secured tothe first and second electrolytes of the first and second electrolyticsub-components, respectively, the intermediate sub-component connectinglayer comprising an electrolyte of the same or different composition ofthe first and second electrolytes and having means for facilitatingsecured operable alignment between the first and second electrolyticsub-components.
 2. The electrolytic cell according to claim 1 whereinthe intermediate sub-component connecting layer further comprises meansfor enabling rolling and bending of the electrolytic cell withoutcausing mechanical degradation to the electrolytic cell or any of theassociated sub-components.
 3. The intermediate sub-component connectinglayer according to claim 1 further including means to enable ionicconductivity.
 4. The electrolytic cell according to claim 1 wherein thefirst electrolytic sub-component includes an anode and the secondelectrolytic sub-component includes a cathode.
 5. The electrolytic cellaccording to claim 1 wherein the intermediate sub-component connectinglayer comprises a polymerizable electrolyte.
 6. The electrolytic cellaccording to claim 1 wherein the intermediate sub-component connectinglayer comprises a high molecular weight polymer.
 7. The intermediatesub-component connecting layer according to claim 1 including means forpenetrating into the first and second electrolytes to, in turn, promotesecurement therebetween.
 8. A process for fabricating an electrolyticcell comprising the steps of: fabricating a first electrolyticsub-component with a first electrolyte; fabricating a secondelectrolytic sub-component with a second electrolyte; applying anintermediate sub-component connecting layer, comprising an at mostpartially cured electrolyte, on to one of the first and secondelectrolytes of the first and second electrolytic sub-components,respectively; attaching the other of the first and second electrolyticsub-components to the intermediate sub-component connecting layer sothat at least a portion of the intermediate sub-component connectinglayer is sandwiched between the first and second electrolytes;orientating the electrolytic cell into a desired configuration whileenabling relative sliding between the first and second electrolyticsub-components so as to facilitate operative alignment therebetween; andfully curing the intermediate sub-component connecting layer after thedesired configuration and alignment have been obtained to, in turn,maintain the electrolytic cell in the desired configuration after suchfull curing.
 9. The process according to claim 8 wherein the steps offabricating the first and second electrolytic sub-components furthercomprise the steps of fabricating at least one of the first and secondelectrolytic sub-components with an electrolyte which is at mostpartially cured.
 10. The process according to claim 9 further includingthe steps of: allowing at least a portion of the intermediatesub-component connecting layer to penetrate into at least a portion ofthe first and second electrolytes prior to the step of fully curing theintermediate sub-component connecting layer; and curing the at least oneof the first and second electrolytes.
 11. The process according to claim8 wherein the first electrolytic sub-component includes an anode and thesecond electrolytic sub-component includes a cathode.
 12. The processaccording to claim 8 wherein the intermediate sub-component connectinglayer comprises an electrolyte having the same composition of at leastone of the first and second electrolytes.
 13. The process according toclaim 8 further including the step of fabricating the intermediatesub-component connecting layer to include a liquid with polymerizablemonomers.
 14. The process according to claim 8 wherein the intermediatesub-component connecting layer is partially cured prior to the step ofapplying the intermediate sub-component connecting layer to the one ofthe first and second electrolytes.